Compositions and methods of manufacturing trivalent filovirus vaccines

ABSTRACT

Disclosed is a stable immunogenic composition capable of eliciting a robust and durable immune response, comprising at least one antigen consisting of a filovirus glycoprotein and at least one nano-emulsion adjuvant which are co-lyophilized and can be reconstituted immediately prior to use. Also disclosed is a vaccine composition comprising at least two antigens, wherein each antigen is specific to a different genus of filovirus and which also comprises at least one nano-emulsion adjuvant.

RELATED APPLICATIONS

This application is a continuation application which claims priorityfrom U.S. patent application Ser. No. 16/879,668 filed on May 20, 2022,now U.S. Pat. No. 11,433,129, which claims the benefit of priority fromU.S. Provisional Application No. 62/850,443 filed on May 20, 2019, thecontents of which are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to the field of recombinant vaccine compositionscombined with a lyophilized nano-emulsion adjuvant. The invention alsorelates to methods of making and using the recombinant, mono- ormultivalent vaccine compositions described herein. The inventionspecifically describes the novel combination of antigen andnano-emulsion adjuvant subjected to co-lyophilization to produce athermostabilized, adjuvanted vaccine which is reconstituted with apharmaceutically acceptable diluent immediately prior to use.Specifically, this invention relates to a recombinant non-replicatingvaccine for filoviruses as well as similar formulations containing atleast one viral glycoprotein antigen co-lyophilized with a nano-emulsionadjuvant.

BACKGROUND OF THE INVENTION

While the frequency of human infection remains relatively minimalcompared to other viruses, the extreme virulence and mortality risk offiloviruses makes such infections an important target for vaccinedevelopment. Despite significant progress with the clinical developmentof several specific vaccine candidates and therapeutics during and afterthe West African outbreak (2013-2016), only one vaccine targeting Zaireebolavirus (EBOV), but no vaccines targeting Sudan ebolavirus (SUDV),the Marburg marburgvirus (MARV) or other filoviruses have receivedregulatory approval. Moreover, protection of a monovalent EBOV vaccineagainst other filoviruses has never been demonstrated in relevantprimate challenge studies requiring the development of additionalmonovalent or multivalent filovirus vaccines.

Filoviruses are enveloped, negative strand RNA viruses. The viral RNA ispackaged with viral nucleoprotein (NP) and the envelope is formed by theassociation of the viral matrix proteins VP40 and VP24 with the membranecontaining the mature surface glycoprotein (GP). GP has been identifiedas the viral protein leading to cell surface binding and membrane fusionand has therefore been selected as the major candidate antigen which mayalso induce virus neutralizing antibodies.

Vaccines containing recombinant proteins require an adjuvant to elicit adurable immune response (Callahan, Shorter, et al., 1991, The importanceof surface charge in the optimization of antigen-adjuvant interactions,Pharm Res, v8:851-8). Adjuvants are molecules, compounds, ormacromolecular complexes that boost the potency and longevity ofspecific immune response to antigens, but cause minimal toxicity orlong-lasting immune effects on their own. Adjuvants can be used toenhance immunogenicity, modulate the type of immune response, reduce theamount of antigen or the number of immunizations required, and improvethe efficacy of vaccines in newborns or elderly. To be maximallyeffective, adjuvants must be selected judiciously and formulatedappropriately based on the desired immune response. However, the numberof adjuvants with acceptable efficacy and safety profiles is limited.

The present state of the art in developing subunit protein immunogensfor human vaccines is to utilize aluminum adjuvants as the startingpoint. The use of aluminum adjuvants is thus fostered by the fact thatthe record of safety of newer formulations cannot match the long termacceptability of aluminum adjuvants in human vaccines. Overall, this hasamounted to a lack of advanced adjuvants that can be applied to vaccinedevelopment, coupled with the fact that several of the most advancedadjuvant formulations/compounds are the property of large pharmaceuticalcompanies. Aluminum-salt adjuvants are currently the most widely usedadjuvants for general use in humans. Aluminum adjuvants are consideredrelatively weak, effective in generation of neutralizing antibodiesagainst certain bacterial antigens, but relatively ineffective atinducing long-lasting cellular immune responses.

The emerging trend in subunit vaccine development has been that it isinsufficient to engineer the protein target itself, but that potent,safe, adjuvant formulations must be utilized as an intrinsic componentof vaccine design, from the earliest feasibility experiments throughclinical testing. The use of formulation technology can result in asignificant decrease in dose levels and number of vaccinations, anincrease in the quality and breadth of the immune response, as well aslong-term, sustained responses to the antigenic target.

Multivalent vaccine compositions are known in the art and have beendescribed in the literature.

WO1993/024148 discloses an invention of multivalent vaccine containingantigens IPV-DPT-Hib-Hepatitis B wherein DPT is adsorbed to AlOH oraluminum phosphate and Hib is adsorbed to only aluminum phosphate,wherein the Hib antigen is used extemporaneously by mixing to the otherantigens just prior to the administration.

WO1997/00697 discloses a DPT-Hib and pertussis multivalent vaccineadsorbed to aluminum phosphate, in which one container has afreeze-dried vaccine and the other container comprises a second antigen.

WO1998/000167 discloses a DTaP-IPV-Hib antigen vaccine and WO1999/13906describes a multiple component vaccine in which certain components maybe reconstituted from a lyophilized state by the other components of thevaccine, or may exist in a single solution, and administers the vaccinein a specially designed container at the time when the vaccination isperformed.

WO2000/07623 describes a multi-component vaccine composition havingacellular pertussis vaccine components (PT and FHA), diphtheria toxoid(DT), tetanus toxoid (TT), a conjugate of a capsular polysaccharide ofHaemophilus influenzae type b and tetanus toxoid or diphtheria toxoid(Hib), Hepatitis B Surface Ag (HBsAg) and inactivated poliovirus (IPV)which may be in a single solution, or certain components may bereconstituted from a lyophilized state by the other components of thevaccine.

WO2002/000249 discloses a capsular polysaccharide of Haemophilusinfluenza type b not adsorbed onto an aluminum adjuvant salt, and two ormore further bacterial polysaccharides which may include whole cellpertussis, tetanus toxoid, diphtheria toxoid, Hepatitis B surfaceantigen (HbsAg), and/or conjugate polysaccharides of N. meningitidestype A, or B, or C as antigens in a single quadrivalent and/or trivalentvaccine.

WO2006/097851 discloses a multivalent vaccine which can be preparedextemporaneously at the time of use by mixing together two componentsthe first component comprising D, T, wP and HBsAg antigens and a secondcomponent comprising a Hib conjugate and one or more meningococcalconjugates.

WO2007/054820 relates to a vaccine composition wherein the D, T, and aPantigens are specifically adsorbed on aluminum hydroxide and the Hib andthe Hep B antigens are adsorbed onto aluminum phosphate which do notexist in a fully liquid stable composition.

WO2008/044611 discloses a method for the preparation of a mixed IPV-DPTvaccine comprising an inactivated poliovirus Sabin strains type I, II,and III grown in Vero cells, a protective antigen against Bordetellapertussis, a diphtheria toxoid and a tetanus toxoid, which involves thestep of producing a poliovirus Sabin strain having a high titer.

WO2019/051098 discloses the production and evaluation of a recombinantsubunit filovirus vaccine using insect cell expressed surfaceglycoprotein (GP) and a highly effective adjuvant. The vaccine providesprotection in humans against filovirus infection, including Ebola virusand Marburg virus, but requiring CoVaccine-HT™ as the adjuvant ofchoice.

Most other vaccine platforms used for filoviruses are either based onrecombinant virus vectors with a GP antigen, pseudo-typed replicationincompetent viruses or virus-like particles. The vaccine candidate ofthe present invention is the only approach based on native,immunoaffinity-purified recombinant protein subunits. There remains aneed in the art for a novel, safe and effective vaccine that can beproduced in a quantity sufficient to protect first responders,healthcare and laboratory workers, the military, and the civilianpopulation, while simultaneously being capable of acquisition intostrategic stockpiles. Furthermore, as the causative agent in a futurepublic health emergency is not known, a multivalent vaccine will bettermeet the needs than single-agent products.

Thermostabilization of proteins with lyophilization is well understood.Moreover, technologies to thermostabilize alum-adjuvanted proteinsubunit vaccines without inducing undue agglomeration or aggregationhave also been demonstrated (WO2008/118691 and WO2012/158978). However,alum is less effective at stimulating cell-mediated immune responses andis not therefore sufficient for all vaccines. The nano-emulsion adjuvantCoVaccine-HT™ has been previously tested as a prepared liquid emulsion(Blom et al., Sucrose fatty acid sulphate esters as novel vaccineadjuvants. Effect of chemical composition. Vaccine 2004; 23:743-54;Hilgers et al., Sucrose fatty acid sulphate esters as novel vaccineadjuvant. Vaccine 24S2 (2006) S2/81-S2/82). Lyophilization ofnano-emulsions has been conducted previously, however lyophilization ofa vaccine nano-emulsion adjuvant, maintaining immunogenicity afterlyophilization, has not been demonstrated. Similarly, co-lyophilizationof a nano-emulsion mixture with one or more separate proteins has alsonot been demonstrated.

SUMMARY OF THE INVENTION

The present invention provides for a stable immunogenic compositioncapable of eliciting a robust and durable immune response, comprising atleast one antigen further comprising a viral glycoprotein and at leastone nano-emulsion adjuvant which are co-lyophilized and can bereconstituted immediately prior to use. In an alternative embodiment,the present invention provides for a vaccine composition comprising atleast two antigens, wherein each antigen is specific to a differentgenus of filovirus and which also comprises at least one nano-emulsionadjuvant. Preferably, the viral glycoprotein is at least one selectedfrom the group of viruses consisting of MARV, SUDV and EBOV. Optionally,the viral glycoprotein is a filovirus glycoprotein.

In another aspect, the present invention provides for a stable,immunogenic composition capable of eliciting a robust and durable immuneresponse, comprising at least one antigen, wherein the at least oneantigen comprises a viral glycoprotein, and at least one adjuvant.Optionally, the composition does not include alum.

Alternatively, the composition of the present invention comprises two ormore antigens, wherein each antigen is specific to a different virus.

In yet another aspect, the composition of the present invention furthercomprises a nano-emulsion adjuvant, wherein the nano-emulsion,preferably, is CoVaccine-HT™. In a preferred embodiment, thenano-emulsion adjuvant is mixed with the antigen prior tolyophilization. Preferably, the nano-emulsion adjuvant that is mixed isCoVaccine-H™.

Another aspect of the invention provides for a method of manufacturing astable immunogenic composition capable of eliciting a robust and durableimmune response to more than one virus, comprising at least twoantigens, wherein each antigen is specific to a different virus from thesame or different families and providing at least one adjuvant, whereinthe adjuvant does not contain alum. Preferably, the adjuvant is anano-emulsion and, most preferably, the adjuvant is CoVaccine-HT′.Alternatively, the adjuvant is combined with the antigen(s) prior tolyophilization. Preferably, the adjuvant to be combined isCoVaccine-HT′.

In another aspect, the present invention provides for a method ofeliciting an immune response in a mammal comprising: (a) providing astable, immunogenic composition capable of eliciting a robust anddurable immune response, comprising at least one antigen, wherein the atleast one antigen comprises a viral glycoprotein, and at least oneadjuvant; (b) reconstituting the composition of (a) prior to use with apharmaceutically acceptable diluent; and (c) administering thecomposition to the mammal in need thereof. Preferably, the compositionis administered up to three separate occasions, resulting in the mammalbeing protected from subsequent infections by the virus associated withthe viral glycoprotein present in the composition.

In yet another aspect of the present invention provides for a stableimmunogenic composition capable of eliciting a robust and durable immuneresponse, comprising at least one nano-emulsion adjuvant, wherein the atleast one nano-emulsion adjuvant is lyophilized and can be reconstitutedimmediately prior to use with an antigen.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures provide illustrative examples of the presentinvention and are incorporated by reference within this disclosure.

FIG. 1 depicts a Coomassie stained SDS-PAGE gel (4-12%) showingMolecular weight standard MW (sizes in kDa), followed by 1 μg each ofsingle step IAC purified EBOV GP (two batches, E1 & E2), MARV GP (M) andSUDV GP (S).

FIG. 2 shows identical Western-blot panels of purified E-GP, M-GP andS-GP, which were generated and probed by EBOV, MARV and SUDV-specificmonoclonals demonstrating viral specificity.

FIG. 3 shows a chromatogram showing size-exclusion-chromatography ofIAC-purified E-GP. The blue graph shows A280 extinction; retention timesof the two peaks represent trimers (right peak) and dimers of trimers(left peak), respectively.

FIG. 4 depicts active or passive immunization protects mice againstweight loss post challenge with ma-EBOV. Body weights normalized toanimal's weight at day 0 (challenge day) are plotted. Directlychallenged vaccines as well as animals receiving anti-GP serum show theleast morbidity; survivors in T-cell transfer groups showed some malaisebut full recovery by day 14 post challenge.

FIG. 5 shows survival of vaccinated and control monkeys (cynomolgusmacaques) after live viral challenge with EBOV. Using either theLog-rank (Mantel-Cox) test or the Gehan-Breslow-Wilcoxon test, both ofthe curves for the vaccinated animals are significantly different fromthe controls (p=0.0082).

FIG. 6 depicts kinetics of viremia post challenge. Viremia wasdetermined by rt-PCR on serum samples taken from individual animals postchallenge—Limit of detection: 3 log 10.

FIG. 7 shows IgG antibody titers to Ebola GP antigen determined by theMIA assay on vaccinated animals. Animals were immunized on days 0, 21,and 42. Antibody levels in vaccinated animals rose rapidly after thefirst and second immunizations and reached a plateau by 14 days postdose 2 (day 35).

FIGS. 8A and 8B depict results of Mouse Antigen balancing experiment;8A: Mouse groups immunized with 10 μg of E-GP and either 3 or 10 μg ofS-GP and M-GP; 8B: Mouse groups immunized with 3 μg of E-GP and either 3or 10 μg of S-GP and M-GP.

FIGS. 9A and 9B show the results of lyophilizing the Co-Vaccine-HT™adjuvant by itself at varying concentrations in a mixture with 9.5% w/vtrehalose, yielding well-formed solid cakes (9A) which can be easilyreconstituted with consistent particle size (9B).

FIG. 10 depicts the immunogenicity of CoVaccine-HT™ at 3, 5, 7 and 10mg/ml co-lyophilized with EBOV GP protein (0.01 or 0.1 mg/ml) and 9.5%w/v trehalose and 10 mM ammonium acetate adjusted to pH 7.Immunogenicity is the same whether generated with the co-lyophilizedproduct or the individual proteins augmented with the liquidnano-emulsion CoVaccine-HT™ product.

FIG. 11 depicts antibody titers in male and female Swiss Webster miceafter vaccination with liquid and lyophilized MARV-GP formulations mixedwith CoVaccine-HT™ after reconstitution and prior to administration onDays 0, 21 and 42 and blood collection on Day 56.

FIGS. 12A, 12B and 12C depict the stability of SUDV-GP preparations whenstored in PBS, in the liquid formulation (without lyophilization) and inthe liquid formulation (after lyophilization). Size exclusionchromatography of the samples immediately after formulation as well asafter 8 weeks storage at 40° C. are demonstrated. The higher molecularweight entities, represented by peaks at earlier time points, arebelieved to be more important for protective immunogenicity. Thelyophilized samples maintained the aggregation profile (16C) whereas thePBS (16A) and liquid formulation (16B) samples showed evidence ofdegradation with decrease in high molecular weight entities and increasein monomeric protein entities.

FIGS. 13A, 13B, 13C and 13D depict the immunogenicity of variousmixtures of viral glycoproteins lyophilized with and without theCoVaccine-HT™ adjuvant. For mixtures lyophilized without adjuvant,adjuvant was added upon reconstitution and before administration to themice. Data show the immunogenicity (Immunoglobulin G concentration inserum) recognizing EBOV GP, MARV GP and SUDV GP respectively generatedin blood collected 2 weeks after the 3^(rd) dose of vaccine. Groups inthe x-axis are identified by formulation conditions with E=EBOV GP,M=MARV GP and S=SUDV GP. FIG. 13A shows the results of Groups 1-12 fromTable 6, FIG. 13B shows the results of Groups 13-24 from Table 6, FIG.13C shows the results of Group 25-30 from Table 6 and FIG. 13D shows theresults of Groups 31-36 from Table 6.

FIGS. 14A, 14B and 14C depict the differences in protein characteristicsacross the EBOV GP, MARV GP and SUDV GP proteins respective. In FIG.14A, representative size-exclusion chromatogram of unincubated EBOV-GPliquid in PBS formulation (black) and 4-week incubated liquid in PBS at40° C. (blue). Peak classifications were made using SEC-MALS molecularweight data (gray markers, right axis). High molecular weight (HMW)species were defined peaks that eluted between 9 and 12.3 minutes,monomer was defined as peaks eluting between 12.3 and 13.9 minutes, andmonomer folding variants were defined as the peaks eluting between 13.9and 17.3 minutes. The molecular weights of the species eluting in eachof the peaks were identified using SEC-MALS, with molecular weightsshown as gray markers on the right axis. In FIGS. 14B and 14C,representative chromatograms are shown for MARV-GP and SUDV-GP with peakmolecular weights from SEC-MALS analysis overlaid and shown as graymarkers.

DETAILED DESCRIPTION OF THE INVENTION

Despite significant progress with the clinical development of severalEBOV vaccine candidates and therapeutics during and after the WestAfrican outbreak, only one vaccine targeting EBOV and none targetingother filoviruses have received regulatory approval. Moreover,protection of a monovalent EBOV vaccine against other filoviruses hasnever been demonstrated in relevant primate challenge studies requiringthe development of additional monovalent or multivalent filovirusvaccines.

We present data of a trivalent vaccine based on recombinant filovirusglycoproteins (GP) from EBOV, MARV and SUDV produced using theDrosophila S2 platform. The highly purified recombinant subunits elicitpotent immune responses in mice, guinea pigs and non-human primates(NHPs) and consistently produce high antigen-specific IgG and surrogatevirus neutralizing antibody titers.

Candidate vaccines show full protection against EBOV infection in rodentand NHP challenge models. Similarly formulated monovalent MARV or SUDVvaccine candidates can protect cynomolgus macaques completely againstinfection with lethal doses of MARV or SUDV and combinations with theEBOV vaccine can be formulated yielding multivalent vaccines retainingefficacy.

Ongoing formulation focuses on thermostabilization of recombinantsubunits by lyophilization. Current data suggest that shelf stability ofat least three months at 40° C. is feasible for each of the threeantigens individually. Most importantly, formulations of antigenslyophilized in the presence of adjuvant are also stable, which shouldenable clinical development of safe and efficacious, field-deployablevaccine candidates for protection against Ebola, Marburg and Sudan VirusDisease. While thermostabilization of subunit proteins uponlyophilization with alum adjuvants has been demonstrated, the use ofnano-emulsion vaccines in this context has not been previouslysuccessfully demonstrated. We have demonstrated that the nano-emulsionadjuvant can not only be lyophilized alone and then reconstituted andstill retain immunogenicity, but that it can be lyophilized with asubunit protein under specific formulation conditions and maintainimmunogenicity.

The present invention describes a solid multivalent filovirus protectionin NHPs, which can be achieved with an adjuvanted formulation featuringa balanced combination of highly purified and defined recombinantfilovirus protein antigens. Additional embodiments include improvedconditions to allow the final product to be stored under the mosteconomical conditions without risking loss of immunogenicity orefficacy. Furthermore, the core platform described herein will beapplied to develop more complex multivalent vaccines that includeantigens from emerging and re-emerging viruses, including but notlimited to, Alphaviruses, Henipaviruses, Arenaviruses, pandemic andseasonal flu and coronaviruses.

In one aspect, the platform of the present invention is based onrecombinant subunit filovirus proteins expressed by stably transformedDrosophila S2 cell lines for development of the trivalent filovirusvaccine candidate. Proper conformation of complex viral proteins isoften problematic to achieve and the production system described hereinhas shown the ability to overcome the challenges and produce correctlyfolded viral glycoproteins with native conformation for a number ofviral vaccine targets. An important advantage to this system is thecapacity of the system to quickly and cost effectively generateproduction scale quantities of high quality viral proteins from stablytransformed cell lines that are key to producing humoral and cellularimmune responses and protective efficacy. This recombinant approach isunique among the filovirus vaccines currently in development,particularly as we use highly purified subunit proteins with a safe,advanced clinical adjuvant and have demonstrated potent efficacy againstEBOV infection in the gold standard cynomolgus macaque model. The novelapproach described herein is based on highly purified recombinantsubunits that provide the unique opportunity to fine-tune the immuneresponse by varying the composition and dosage of individual viralantigens to achieve the desired broad-spectrum immunity. Similarlybalanced immunity is very difficult, if not impossible, to achieve forvirally vectored platforms, DNA vaccines, and even VLP's.

In another embodiment, the recombinant subunit vaccine platform of thepresent invention achieves the high quality of its antigens by the useof antigen-specific immunoaffinity chromatography (IAC) which rejectsany protein with misfolded epitope regions. Therefore, there is a needfor sufficient quantities of antibodies produced under conditions thatlend themselves to rapid, cost-effective GMP manufacturing.

EXAMPLES

The following examples illustrate the various embodiments of the presentinvention and are not meant to be limiting in scope based on suchexamples.

Expression and Purification of Subunit Proteins:

All antigens used for the studies described herein have been expressedusing stably transformed Drosophila cell lines in 1-5L batches in a WAVEbioreactor (GE Lifesciences, Piscataway, N.J.). Expression levels of allselected cell lines (for MARV-GP after two rounds of subcloning) havebeen stable in the range of 10-100 mg/L. The GP subunits weresubsequently purified by single-step immunoaffinity chromatography (IAC)using specific affinity columns for each individual protein (see FIG. 1). To date, more than 200 mg of EBOV GP (E-GP), 100 mg of MARV GP, and100 mg of SUDV GP with purity levels between 90-95% (based on SDS-PAGE)have been produced. EBOV, SUDV and MARV GP's are highly pure and showgood antigenic specificity (FIG. 2 ).

To establish the equivalency of plant- and murine hybridoma-derivedmonoclonal antibodies, we tested a plant- and hybridoma-derived anti-GPantibody (13C6—description can be found in Olinger et al. 2012). A 1.5m1column containing 15 mg of immobilized plant-expressed antibody bound0.2 mg antigen per batch while a column using hybridoma-derived antibody(100 mg immobilized on 10 ml NHS-sepharose) bound between 1-1.3 mg perbatch proving that the plant-expressed antibody achieves similar yieldsand purity (>90%) of E-GP. We now routinely use plant-expressedmonoclonal antibodies for production of filovirus GPs. When analyzingthe size of purified E-GP, we discovered that it mainly forms trimers(native conformation on virus particles) as well as dimers of trimers(FIG. 3 ). We separated the two populations of oligomers by FPLC andestablished their protective potential in guinea pigs as identical(Lehrer et al., Recombinant Subunit Vaccines Protect Guinea Pigs FromLethal Ebola Virus Challenge. Vaccine 2019; November 8;37(47):6942-6950). We therefore don't think that a polishing step willbe required in establishing our final antigen purification procedure.

Immunogenicity and Efficacy in Mice:

Immunogenicity of purified EBOV GP subunits was tested in Balb/c mice.First, individual antigens were tested in formulations with fourfunctionally different adjuvants: ISA-51 (water-in-oil emulsion; Seppic,Fairfield, N.J.), GPI-0100 (saponin-based; Hawaii Biotech, Inc.,Honolulu, Hi.), CoVaccine-HT™ (emulsion-based; BTG, London, UK) and RibiR-700 (monophosphoryl lipid A and trehalose dicorynomycolate;Sigma-Aldrich). Excellent humoral and cell-mediated responses were seen,especially for CoVaccine HT™ and GPI-0100 (data not shown). ELISAantibody responses to the antigens were evident after one immunization,and as expected, increased following a booster injection. E-GPadministered at doses from 1-9 μg showed a typical dose-related response(Lehrer et al., Recombinant proteins of Zaire ebolavirus induce potenthumoral and cellular immune responses and protect against live virusinfection in mice. Vaccine 2018; 36(22):3090-3100).

For the first efficacy study, Balb/c mice were immunized at days 0, 28and 56 with formulations containing IAC purified recombinant E-GP withor without adjuvants. The animals were infected 23 days after the thirdimmunization by i.p. injection with 100 pfu (3000 LD50) of mouse adaptedEBOV (MA-EBOV). The results of the experiment are shown in Table 1.

TABLE 1 Recombinant Ebola virus GP subunits protect mice against livevirus challenge Survival (day 20 Group post no. Immunogen^(a) Adjuvantchallenge)^(b) Morbidity^(c) 1 GP NONE 70% All survivors sick 2 GPGPI-0100 90% All survivors sick 3 GP CoVaccine HT 100%  None sick 4 NONENONE  0% No survivors 5 NONE GPI-0100 10% Survivor sick 6 NONE CoVaccineHT  0% No survivors ^(a)Mice were immunized with 10 μg antigen (s.c.)^(b)10 animals per group, except groups 4 and 6 with 9 animals each.^(c)Morbid (sick) animals showed any signs of illness (e.g. ruffledfur).

Interestingly, animals immunized three times with 10 μg of EBOV GP (noadjuvant) showed 70% protection, similar to protection reported afterfour doses of the best adjuvanted formulations of recombinant “Ebolaimmune complexes” (Phoolcharoen et al. 2011) and also similar inprotection achieved with four doses of a recombinant GP-Fc fusionprotein administered to mice in Freund's adjuvant (Konduru et al. 2011),but significantly better than protective efficacy of Novavax's GPnanoparticles when given alone or in combination with Alum (Bengtsson etal. 2016). GP formulated with CoVaccine-HT′ showed 100% protectiveefficacy against both morbidity and mortality emphasizing the importanceof adjuvant selection for protection. The excellent protective efficacyof the adjuvanted formulations, in combination with the finding ofsurprisingly good protective efficacy with unadjuvanted GP, stronglysupport the use of this protein as a vaccine candidate. In comparison,with and without adjuvant, recombinant GP yields immune responsesequivalent or superior to responses seen with Ebola virus-like particles(VLPs) in mice (Warfield et al. 2003, 2007), without the productionchallenges associated with VLPs that are being produced similarly toviruses using centrifugation methods and are prone to be affected bybatch-to-batch consistency and stability issues.

Recombinant EBOV GP Subunit with CoVaccine Adjuvant Elicits ProtectiveCellular and Humoral Responses:

To evaluate the humoral and cellular immune mechanisms underlyingprotection conferred by GP, a further study employing passive protectionby transfer of immune serum and adoptive protection by transfer ofimmune T-cells was conducted. A formulation containing 10 μg E-GPprotein and CoVaccine-HT™ was administered three times at 4-weekintervals to 35 Balb/c mice. Fourteen days after the last dose, 30 micewere euthanized and serum samples collected by cardiac puncture. Samplesfrom all animals were pooled, and then 1 ml immune serum each wastransferred i.p. to naïve Balb/c mice. Splenocytes were prepared fromthe spleens of vaccinated mice and T-cells separated by negativeselection (using MACs separation (Invitrogen, Carlsbad, Calif.)).T-cells were transferred at two dose levels. All mice, including theremaining five vaccines (“direct challenge”) were infected approximately24 hours post serum/splenocyte transfer by i.p. injection with 1000 pfu(30000 LD₅₀) of MA-EBOV. Surviving animals were euthanized 28 days postchallenge and serum samples collected. Pre-challenge sera collected fromimmunized mice during the immunization phase were analyzed for antigenspecific ELISA IgG titers. GP immunized mice showed GMT EC_(50s)>100,000after two and three doses. Survival is shown in Table 2.

TABLE 2 Passive transfer of serum or adoptive transfer of immune T cellsprotects naïve Balb/c mice against challenge with MA-EBOV (#survivors/total # challenged) Direct Serum T cells T cells VaccineChallenge Transfer¹ (high²) (low³) 10 μg GP + 5/5 9/10 7/10 5/10CoVaccine HT >102400 (GP⁴) 11324 (GP) CoVaccine HT 0/5 0/10 — — ¹1 ml ofimmune serum per mouse administered i.p. ²1.5 × 10⁷ T-cells/mouseadministered i.p. ³1.5 × 10⁶ T-cells/mouse administered i.p. ⁴anti-GPIgG titer (GMT EC50) 28 d post challenge

Direct challenge controls showed full protection as previously seen. Asexpected, GP-specific antiserum provided almost complete protection tothe naïve recipients. Interestingly, the protected animals receivingGP-specific serum as well as the directly challenged GP-vaccines showedno weight loss (FIG. 4 ), which is seen as an indicator of morbidity inthe mouse model (Bray et al. 1998). Furthermore, post-challenge ELISAtiters on directly infected mice showed that anti-GP levels were in thesame range as pre-challenge sera, while anti-VP40 titers stayedextremely low (˜1.5 logs below VP40 titers observed in otherpost-challenge samples; data not shown). This suggests that very little,if any, viral replication occurred. We postulate further, that inpassively immunized mice (serum transfer) the virus was effectivelyneutralized, eliminating morbidity. Immune T-cells were able to protectthe majority of naïve recipients from death and a dose-dependency ofsurvival and weight loss caused by infection could be seen.Post-challenge induction of GP and VP40-specific IgG responses in thesenaïve animals can be explained by a limited degree of viral replication.In sum, this experiment demonstrated that recombinant EBOV GP not onlyinduces potent humoral responses, but also generates the criticalfunctional cellular immune responses indicated by the ability of immuneT cells to transfer protection to naïve mice (Lehrer et al., Recombinantproteins of Zaire ebolavirus induce potent humoral and cellular immuneresponses and protect against live virus infection in mice. Vaccine2018; 36(22):3090-3100).

Non-Human Primate Immunogenicity and Efficacy:

Cynomolgus macaques (Macaca fascicularis) were chosen to conduct anon-human primate immunogenicity and efficacy experiment based on anEBOV challenge model originally developed by Dr. Thomas Geisbert atUSMARIID (now Galveston National Laboratory/UTMB).

This experiment used animals of both sexes and older (5-15 years old)than typically used for EBOV challenge studies found in the literature(typically 3-4 years old). We believe that this better reflects arepresentative age distribution than basing development only on youngadults. One group of animals was immunized by the intramuscular route(IM) three times at three week intervals with 25 μg of EBOV GPformulated with 10 mg of CoVaccine-HT™ adjuvant, a second group wasimmunized with an alternate formulation (containing GP with recombinantEBOV VP24 and VP40 proteins produced similarly to EBOV GP and using thesame adjuvant), while the control group was given only adjuvant. Fourweeks after the last vaccination, all animals were challenged by thesubcutaneous route (SC) with 1000 LD₅₀ of EBOV, strain Kikwit (7Uisolate 199510621, stock number R4414 (Kugelman et al. 2016). Animalswere monitored twice daily for morbidity and mortality for up to 28days. Results are given in Table 3 below and survival curves are shownin FIG. 5 .

TABLE 3 Results from EBOV challenge study in cynomolgus macaques #survivors/total # of Group Vaccine composition animals challenged 1 25μg EBOV GP + 10 mg  5/6^(a) CoVaccine HT adjuvant 2 Alternate vaccineformulation^(b) 5/6 3 Adjuvant only 0/2 ^(a)The single animal that metthe euthanasia criteria in group 1 was a 15-year-old male and did notshow any signs of Ebola Virus Disease (EVD) (based on clinical chemistryand the necropsy report). The animal that had to be euthanized in group2 was also a 15-year-old male who showed some clinical markers of EVDbased on pathology observed in the necropsy. ^(b)The alternateformulation contained EBOV GP + VP24 and VP40 proteins (produced andpurified similarly to GP) with the same adjuvant.

Viremia was determined by rt-PCR. Sera from all animals were collectedat 3-4 day intervals until death (controls) or day 14 (vaccines). Theresults are shown in FIG. 6 , which clearly demonstrate the dramaticinhibition of viremia as a result of vaccination with the recombinantsubunit monovalent Ebola vaccine. The animals vaccinated with thealternate formulation showed slightly higher virus load than animalsvaccinated with GP+CoVaccine-HT™.

Antibody titers were determined on serum samples from vaccinated animalsat various time points post vaccination but prior to challenge. Theresults shown in FIG. 7 demonstrate a robust humoral immune response.There is no statistically significant difference between titers elicitedby either vaccine formulation.

The results of the NHP efficacy study demonstrated full vaccineprotection against live EBOV challenge, successful inhibition ofviremia, and high antibody titers following vaccination with potenttiters already after two doses.

Antigen-Balancing Experiment:

An extensive mouse antigen balancing experiment has already beenconducted. Swiss Webster mice (groups of 8 mice; 4M, 4F) wereadministered three doses (IM), 3 weeks apart of either 3 or 10 μg ofeach GP antigen, formulated with CoVaccine-HT™ adjuvant. The dose rangeselection was based on earlier mouse experiments that identified anoptimal E-GP dose between 3 and 10 μg. Antibody titers (IgG) to eachantigen were measured by the MIA assay for each filovirus antigen at twoweeks after each dose. The results are shown in FIG. 8A, FIG. 8B.

Immunogenicity of Lyophilized Adjuvant with EBOV-GP:

We conducted experiments evaluating the ability to lyophilize theadjuvant CoVaccine-HT™ under similar conditions to the GP proteins.CoVaccine-HT™ at various concentrations was mixed with 9.5% w/vtrehalose and lyophilized. The resulting product showed white,well-formed cakes consistent with successful lyophilization (FIG. 9A).Moreover each vial was reconstituted with water and shown to havemaintained the same particle size distribution as present prior tolyophilization (FIG. 9B).

Previous studies have shown that EBOV GP protein can be lyophilized andreconstituted while generating appropriate immune responses (Chisholm etal., Thermostable Ebola Virus Vaccine Formulations Lyophilized in thePresence of Aluminum Hydroxide. Eur J Pharm Biopharm 2019 March;136:213-220). We also co-lyophilized the CoVaccine-HT™ at concentrationsof 3, 5, 7 and 10 mg/ml with EBOV GP protein at concentrations of 0.01and 0.1 mg/ml with 9.5% w/v trehalose. The resulting lyophilizedcompositions were tested for immunogenicity in BALB/c mice byadministration on Days 0, 21 and 42 with blood draws on Day 56. Theresulting blood samples revealed significant antibody titers, equivalentbetween the original liquid formulations and the lyophilizedformulations, demonstrating the preservation of immunogenicity of thesingle product during the lyophilization process (FIG. 10 ).

Compatibility of the Formulation and Lyophilization Conditions with theMARV-GP Protein:

A study was created to determine the effects of salt, pH, and surfactanton the stability of the MARV-GP over time and temperature. Nineformulations were evaluated with varying levels of pH, salt (ammoniumacetate) concentration, and surfactant (polysorbate-20) concentration.Formulations were analyzed both before and after lyophilization. A shortincubation was done on lyophilized samples for 2 weeks at 50° C. toimmediately evaluate immunogenicity and stability, while a longerincubation for 12 weeks at 25° C. and 40° C. was done to see the longerterm stability of the formulations. The results of the study aresummarized below at Table 4.

TABLE 4 MARV-GP Formulation Conditions Salt level (ammonium SurfactantTime points Group acetate) pH (PS-20) Trehalose tested 1 25 mM 7 0 mg/mL9.5% LYO: 0 wk, 2 wk 50 C., (w/v) 12 wk 25 C., 12 wk 40 C. LIQ: 0 wk, 12wk 25 C., 12 wk 40 C. 2 50 mM 7 0 mg/mL 9.5% LYO: 0 wk, 2 wk 50 C.,(w/v) 12 wk 25 C., 12 wk 40 C. LIQ: 0 wk, 12 wk 25 C., 12 wk 40 C. 3 100mM  7 0 mg/mL 9.5% LYO: 0 wk, 2 wk 50 C., (w/v) 12 wk 25 C., 12 wk 40 C.LIQ: 0 wk, 12 wk 25 C., 12 wk 40 C. 4 10 mM 7 1/2x CMC = 9.5% LYO: 0 wk,2 wk 50 C., 0.03 mg/mL (w/v) 12 wk 25 C., 12 wk 40 C. LIQ: 0 wk, 12 wk25 C., 12 wk 40 C. 5 10 mM 7 2x CMC = 9.5% LYO: 0 wk, 2 wk 50 C., 0.12mg/mL (w/v) 12 wk 25 C., 12 wk 40 C. LIQ: 0 wk, 12 wk 25 C., 12 wk 40 C.6 10 mM 7 4x CMC = 9.5% LYO: 0 wk, 2 wk 50 C., 0.24 mg/mL (w/v) 12 wk 25C., 12 wk 40 C. LIQ: 0 wk, 12 wk 25 C., 12 wk 40 C. 7 10 mM 5.5 0 mg/mL9.5% LYO: 0 wk, 2 wk 50 C., (w/v) 12 wk 25 C., 12 wk 40 C. LIQ: 0 wk, 12wk 25 C., 12 wk 40 C. 8 10 mM 6.5 0 mg/mL 9.5% LYO: 0 wk, 2 wk 50 C.,(w/v) 12 wk 25 C., 12 wk 40 C. LIQ: 0 wk, 12 wk 25 C., 12 wk 40 C. 9 10mM 7.5 0 mg/mL 9.5% LYO: 0 wk, 2 wk 50 C., (w/v) 12 wk 25 C., 12 wk 40C. LIQ: 0 wk, 12 wk 25 C., 12 wk 40 C.

Immunogenicity testing of the samples stored for 12 weeks at 40° C.demonstrated that the formulation retained immunogenicity in BALB/c micewhen dosed on Days 0, 21 and 42 with blood samples drawn for evaluationon Day 56 (FIG. 11 ).

Compatibility of the Formulation and Lyophilization Conditions with theSUDV-GP Protein:

A study was performed to determine the effects of salt on the stabilityof the SUDV-GP over time and temperature. The study is ongoing withanalytical results (size exclusion chromatography) at the 8 week timepoint suggesting that the lyophilized formulations experienced the leastamount of change (FIG. 12C) compared to the protein stored in PBS (FIG.12A) or in the liquid formulation prior to lyophilization (FIG. 12B).The results of the study are summarized below at Table 5.

TABLE 5 SUDV-GP Formulation Conditions Salt level (ammonium SurfactantTreha- Time points Group acetate) pH (PS-20) lose tested 1 10 mM 7 0mg/mL 9.5% LYO/LIQ: 0, 4, 8 (w/v) and 12 wk at 25 C. and 40 C. 2 50 mM 70 mg/mL 9.5% LYO/LIQ: 0, 4, 8 (w/v) and 12 wk at 25 C. and 40 C. 3 100mM  7 0 mg/mL 9.5% LYO/LIQ: 0, 4, 8 (w/v) and 12 wk at 25 C. and 40 C. 4 0 mM NA 0 mg/ml  0 Protein in PBS “as is”: 0, 4, 8 and 12 wk at 25 C.and 40 C.Compatibility of the Formulation and Lyophilization Conditions with theTriValent Vaccine (EBOV-GP, MARV-GP and SUDV-GP) with and withoutCoVaccine-HT™ in the Same Vial:

Mixtures of all three GP subunits with and without co-lyophilizedCoVaccine-HT™ have been prepared and immunogenicity assessed in rodents.Table 6 shows a comparison of the various mixtures as analyzed.

Mice were immunized intramuscularly with 100 μl (50 μl/hind leg) vaccinethree times at 3-week intervals. Blood was taken two weeks after eachdosing. Mice were exsanguinated at the third bleed. Antibody titers weremeasured on the blood by Multiplex Immunoassay using the Luminex™system.

TABLE 6 TriValent Formulations E-GP S-GP M-GP CoV HT Ammonium ID [μg][μg] [μg] [mg] Acetate Trehalose pH 1 0.1 10 mM 9.5% w/v 7 2 0.3 10 mM9.5% w/v 7 3 1.0 10 mM 9.5% w/v 7 4 3.0 10 mM 9.5% w/v 7 5 0.1 10 mM9.5% w/v 7 6 0.3 10 mM 9.5% w/v 7 7 1.0 10 mM 9.5% w/v 7 8 3.0 10 mM9.5% w/v 7 9 0.1 10 mM 9.5% w/v 7 10 0.3 10 mM 9.5% w/v 7 11 1.0 10 mM9.5% w/v 7 12 3.0 10 mM 9.5% w/v 7 13 0.1 0.1 0.1 10 mM 9.5% w/v 7 140.3 0.3 0.3 10 mM 9.5% w/v 7 15 1.0 1.0 1.0 10 mM 9.5% w/v 7 16 3.0 3.03.0 10 mM 9.5% w/v 7 17 0.1 0.04 0.1 10 mM 9.5% w/v 7 18 0.3 0.12 0.3 10mM 9.5% w/v 7 19 1.0 0.4 1.0 10 mM 9.5% w/v 7 20 3.0 1.2 3.0 10 mM 9.5%w/v 7 21 0.05 0.05 0.1 10 mM 9.5% w/v 7 22 0.15 0.15 0.3 10 mM 9.5% w/v7 23 0.5 0.5 1.0 10 mM 9.5% w/v 7 24 1.5 1.5 3.0 10 mM 9.5% w/v 7 25 0.10.3 10 mM 9.5% w/v 7 26 1.0 0.3 10 mM 9.5% w/v 7 27 0.1 0.3 10 mM 9.5%w/v 7 28 1.0 0.3 10 mM 9.5% w/v 7 29 0.1 0.3 10 mM 9.5% w/v 7 30 1.0 0.310 mM 9.5% w/v 7 31 0.1 0.1 0.1 0.3 10 mM 9.5% w/v 7 32 1.0 1.0 1.0 0.310 mM 9.5% w/v 7 33 0.1 0.04 0.1 0.3 10 mM 9.5% w/v 7 34 1.0 0.4 1.0 0.310 mM 9.5% w/v 7 35 0.05 0.05 0.1 0.3 10 mM 9.5% w/v 7 36 0.5 0.5 1.00.3 10 mM 9.5% w/v 7

Immunogenicity was similar if CoVaccine-HT™ was co-lyophilized with theGP proteins (groups 25-36) as compared to when CoVaccine-HT™ wasco-injected, but not co-lyophilized, with the GP protein mixtures(Groups 1-24), as shown in FIG. 13 .

EBOV GP, MARV GP and SUDV GP are Distinct Viral Glycoproteins:

Each GP protein tested was a distinct protein species, with uniqueoligomerization and glycosylation. Despite these differences, eachprotein was compatible with the CoVaccine-HT™ adjuvant, with theselected formulation conditions and with co-lyophilization with theadjuvant under the selected formulation conditions.

The EBOV GP protein is predominantly formed as multimers, specificallytrimers and higher molecular weight species, including potentiallydimers of trimers, as shown in the SEC-MALS assessment of molecularweight of the peaks identified under size exclusion chromatography (FIG.14 a It was determined that the peak eluting at 11 minutes was anEBOV-GP trimer (with an average molecular weight of 273.1±9.5 kDa) andthe peak eluting at 13 minutes was monomer (107.6±2.8 kDa). The peaksthat eluted later than the monomer were determined to be foldingvariants of the EBOV-GP monomer because they had the same molecularweight (106.8±1.7 kDa) as the monomer but had longer retention times insize exclusion chromatography due to their increased interaction withthe stationary phase. Peaks eluting earlier than 11 minutes wereassociated with species having molecular weights >877 kDa, and wereconsidered to be mixtures of oligomers larger than a trimer and weretherefore classified as BMW species along with the trimer peak.

The MARV GP protein is predominantly formed as a single homogenousmultimer, as shown in FIG. 14 b . Unlike EBOV-GP, for MARV-GP only onespecies was present in the chromatogram, indicating MARV-GP assembly wasnot prone to dissociation. This species was identified as an oligomerthat was around 760 kDa.

The SUDV GP protein is also predominantly found as multimers, with abroader mix of high molecular weight aggregates as compared to EBOV GP(FIG. 14 c ). SUDV-GP (FIG. 7 b ), however, was similar to EBOV-GP inthat there were multiple species present, including monomeric foldingvariants that have the same molecular weight as the monomer but elute atdifferent times.

Compatibility of the Formulation and Lyophilization Conditions with aSARS-CoV-2 Vaccine (Spike Protein) with and without CoVaccine-HT′ in theSame Vial:

The Spike protein of SARS-CoV-2 is a trimeric glycoprotein and will besubjected to the same formulation conditions as the other viralglycoprotein examples, as shown in Table 7. These formulations will betested in mice and the combination, lyophilized product(“Co-Lyophilized” in Table 7) will be shown to be at least asimmunogenic as the other protein formulations using the same antigen.

TABLE 7 Spike Protein Formulations Spike CoVaccine Formulation proteinHT ™ Name (μg) (mg) Excipients Lyophilized CO-Lyophilized 25 0.3 10 mMsodium Yes acetate 9.5% trehalose Protein 25 — 10 mM sodium Yeslyophilized* acetate 9.5% trehalose Protein 25 — Phosphate No liquid*buffered saline CoVaccine — 0.3 — No *CoVaccine adjuvant will be addedto a dose of 0.3 mg/mouse immediately prior to injectionEach formulation will be injected into 6 Swiss Webster mice on Days 1,21 and 42 with blood collected on days 14, 35 and 56. Anti-Sars-CoV-2IgG titers will be determined for blood collected on Days 14, 35 and 56and compared.

In view of the above examples, the following conclusions were drawn:

-   -   1. Full protection against EBOV in mouse, guinea pig and, most        relevant, non-human primate models warranting further        development of the vaccine. Our preliminary efficacy data        demonstrate that the EBOV vaccine has been formulated        successfully. With its demonstrated excellent safety profile (no        adverse reactions observed in non-human primates) and good        efficacy against high titer challenge it should be ready to        advance into clinical development.    -   2. Surface glycoproteins (GP) have been produced and purified        successfully from MARV and SUDV in addition to EBOV, and their        immunogenicity and efficacy against live-virus challenge        demonstrated in non-human primates. Similarly, MARV-GP and        SUDV-GP are compatible with the formulation conditions        identified for the EBOV-GP protein (10 mM ammonium acetate, 9.5%        w/v trehalose, pH 7, lyophilized). Consequently, we believe that        we have defined the basis for a filovirus vaccine effective        against these three viruses.    -   3. Storage stability in lyophilized form of the vaccine        formulation has been shown by biochemical/biophysical methods        and maintenance of immunogenicity has been demonstrated in mice        for EBOV-GP, MARV-GP and SUDV-GP as well as for selected        mixtures of glycoproteins. It is believed that this attribute of        the recombinant subunit vaccine formulation in combination with        excellent stability of the selected clinical stage adjuvant        allows for the development of a safe and effective trivalent        filovirus vaccine that will be suitable for deployment in the        field under conditions where other vaccines would encounter        difficulties due to cold-chain storage requirements.    -   4. Lyophilization of the preferred CoVaccine-HT™ nanoemulsion        adjuvant has demonstrated well-formed cakes with surprisingly        well retained particulate size after reconstitution. Moreover,        the combined protein and adjuvant composition co-lyophilized        maintains its immunogenic profile in rodents and non-human        primates, as demonstrated with EBOV-GP and MARV-GP as well as        for bi- and trivalent formulations lyophilized with        CoVaccine-HT™.        Laboratory Assays and Methods:

Multiplex Immunoassay (MIA): We have developed a bead-based assay inwhich magnetic beads (MagPix) are coated with our recombinant filovirusantigens, allowing the generation of sample- and reagent-sparingmultiplex antibody assays.

Lyophilization of antigens: Vaccine formulation used in preliminary datasection: 0.1 mg/mL EBOV GP, 10 mM ammonium acetate pH 7, 9.5% (w/v)trehalose±0.5 mg/mL aluminum hydroxide. Lyophilizer shelves werepre-cooled to −10° C.; shelf temperature was decreased at a rate of 0.5°C./min to −40° C. and then held at −40° C. for 1 hour. Primary drying at60 mTorr and −20° C. for 20 hours. Secondary drying at 60 mTorr withtemperature gradient to 0° C., then 30° C. followed by hold at 30° C.for 5 hours.

Size exclusion chromatography: SE-HPLC can be used to monitor theassembly state of the protein. SE-HPLC separates protein samples usingtwo columns, a guard column and a size exclusion column. The guardcolumn acts as a filter to remove large particles, like those greaterthan 1,000,000 g/mol, to protect the more sensitive HPLC column. Thesize exclusion column works by trapping smaller molecules in the poresof the column, so smaller molecules have longer elution times. Areasunder the chromatograms (collected as light absorption at 280 nm) can bedirectly correlated to the mass of protein in the sample.

Size exclusion chromatography with multi-angle light scattering: Toseparate and then determine the molecular weights of glycoproteinspecies, unincubated protein samples were analyzed using SEC-MALS.SEC-MALS was performed using an ÄKTApurifier™ system (GE Healthcare LifeSciences, Marlborough, Mass.) with an in-line Wyatt Dawn Heleos II18-angle light scattering detector (Santa Barbara, Calif.) and a WyattOptilab rEX refractive index detector. Samples used were stock solutionsof EBOV-GP, MARV-GP, and SUDV-GP stored in PBS to allow for sufficientloading to obtain accurate molecular weights for each protein peak thateluted form the column. Before injection, samples were filtered througha 0.1 μm centrifugal filter (MilliporeSigma, Burlington, Mass.). Thesupernatant was passed through a TSKgel guard column and a TSKgelG3000SWXL column with the same mobile phase as used in SE-HPLCexperiments. The system was operated at a flow rate of 0.5 mL/min.

As used in this specification and in the appended claims, the singularforms include the plural forms. For example the terms “a,” “an,” and“the” include plural references unless the content clearly dictatesotherwise. Additionally, the term “at least” preceding a series ofelements is to be understood as referring to every element in theseries. The inventions illustratively described herein can suitably bepracticed in the absence of any element or elements, limitation orlimitations, not specifically disclosed herein. Thus, for example, theterms “comprising,” “including,” “containing,” etc. shall be readexpansively and without limitation. Additionally, the terms andexpressions employed herein have been used as terms of description andnot of limitation, and there is no intention in the use of such termsand expressions of excluding any equivalents of the future shown anddescribed or any portion thereof, and it is recognized that variousmodifications are possible within the scope of the invention claimed.Thus, it should be understood that although the present invention hasbeen specifically disclosed by preferred embodiments and optionalfeatures, modification and variation of the inventions herein disclosedcan be resorted by those skilled in the art, and that such modificationsand variations are considered to be within the scope of the inventionsdisclosed herein. The inventions have been described broadly andgenerically herein. Each of the narrower species and subgenericgroupings falling within the scope of the generic disclosure also formpart of these inventions. This includes the generic description of eachinvention with a proviso or negative limitation removing any subjectmatter from the genus, regardless of whether or not the excisedmaterials specifically resided therein. In addition, where features oraspects of an invention are described in terms of the Markush group,those schooled in the art will recognize that the invention is alsothereby described in terms of any individual member or subgroup ofmembers of the Markush group. It is also to be understood that the abovedescription is intended to be illustrative and not restrictive. Manyembodiments will be apparent to those of in the art upon reviewing theabove description. The scope of the invention should therefore, bedetermined not with reference to the above description, but shouldinstead be determined with reference to the appended claims, along withthe full scope of equivalents to which such claims are entitled. Thoseskilled in the art will recognize, or will be able to ascertain using nomore than routine experimentation, many equivalents to the specificembodiments of the invention described. Such equivalents are intended tobe encompassed by the following claims.

What is claimed is:
 1. A stable, immunogenic composition capable ofeliciting a robust and durable immune response, comprising at least oneantigen, wherein the at least one antigen comprises a viralglycoprotein, and at least one adjuvant, wherein the at least oneadjuvant comprises sucrose fatty acid sulphate esters and wherein the atleast one antigen and the at least one adjuvant are co-lyophilized andreconstituted immediately prior to use.
 2. The composition of claim 1,wherein the composition does not include alum.
 3. The composition ofclaim 1, wherein the composition comprises two or more antigens, whereineach antigen is specific to a different virus.
 4. A method of elicitingan immune response in a mammal comprising: (a) providing the compositionof claim 1; (b) reconstituting the composition of (a) prior to use witha pharmaceutically acceptable diluent; and (c) administering thecomposition to the mammal in need thereof.
 5. The method of claim 4,wherein the composition is administered up to three separate occasions,resulting in the mammal being protected from subsequent infections bythe virus associated with the viral glycoprotein present in thecomposition.
 6. A stable immunogenic composition capable of eliciting arobust and durable immune response, comprising at least two antigens,wherein each antigen is a viral glycoprotein specific to a differentgenus of filovirus and at least one nano-emulsion adjuvant.
 7. Thecomposition of claim 6, wherein the viral glycoprotein is at least oneselected from the group consisting of Marburg marburgvirus (MARV), Sudanebolavirus (SUDV) and Zaire ebolavirus (EBOV).
 8. A method ofmanufacturing a stable immunogenic composition capable of eliciting arobust and durable immune response to more than one virus, comprising atleast two antigens, wherein each antigen is specific to a differentvirus from the same or different families and providing at least oneadjuvant, wherein the at least one adjuvant comprises sucrose fatty acidsulphate esters and wherein the at least one antigen and the at leastone adjuvant are co-lyophilized and reconstituted immediately prior touse, and further wherein the at least one adjuvant does not containalum.